Catheter with progressively compliant tip

Abstract

The present invention relates to an improved intravascular catheter. The intravascular catheter involves the use of a progressively compliant tip at the distal end of the catheter body. This progressively compliant tip utilizes an endmost tubular member having a first softness and an intermediate tubular member having a second softness. The low temperature thermoplastic overcoat on the catheter body has a third softness which is significantly lower than the first and second degrees of softness exhibited by the other tubular members. The endmost member, intermediate member and thermoplastic overcoat are joined together by heat formed, blended tubular regions, each having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof. The incrementally increasing intermediate softness characteristic of these blended regions is formed by heated diffusion of the endmost member with the intermediate member, and further by the heated diffusion of the intermediate tubular member with the polymer overcoat. Accordingly ,the softness and hence the compliancy of the distal end region of the catheter tip changes from the distal end of the tip (very soft) to the first blended tubular region (high-medium degree of softness), to the intermediate tubular member (medium degree of softness), to the further blended tubular region (medium-low degree of softness), and ultimately to the thermoplastic overcoat (low degree of softness).

What is claimed is: 
     
       1. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body made of a high temperature thermoplastic having a low coefficient of friction and having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof.   
     
     
       2. A catheter as claimed in claim I wherein said endmost section protrudes beyond the distal end of said catheter body. 
     
     
       3. A catheter as claimed in claim I wherein at least one of said blended regions has an axial length substantially equal to an axial length of one of said endmost section and said other section. 
     
     
       4. A catheter as claimed in claim 1 wherein an outer dimension of said endmost and said other tubular section is substantially equivalent to an outer dimension of said overcoat. 
     
     
       5. A catheter as claimed in claim 1 wherein said first softness is within the range of 55-75 D Shore hardness, said second softness is within the range of 30-45 D Shore hardness, and said third softness is less than said first softness and within the range of 55-75 D Shore hardness. 
     
     
       6. A catheter as claimed in claim 1 wherein said endmost section, said other section and said overcoat are color coded, each with a distinct color. 
     
     
       7. A catheter as claimed in claim 6 wherein said blended regions exhibit a color blend generally indicative of said incrementally increasing softness characteristic. 
     
     
       8. A catheter as claimed in claim 1 wherein the blended region between said other section and said overcoat contains incrementally greater amounts of said overcoat dependent upon the distance to said distal end of said catheter. 
     
     
       9. A catheter as claimed in claim 1 wherein said low temperature thermoplastic overcoat, said low temperature thermoplastic endmost section, and said low temperature thermoplastic other section all melt at temperatures below approximately 300 degrees Centigrade. 
     
     
       10. A catheter as claimed in claim 9 wherein said catheter body is an extruded high temperature elongated thermoplastic tube which is not significantly affected in a temperature range between ambient temperature and 300 degrees Centigrade. 
     
     
       11. A catheter as claimed in claim 10 wherein said catheter body is made of a high temperature thermoplastic having a low coefficient of friction and said endmost section protrudes beyond the distal end of said catheter body. 
     
     
       12. A catheter as claimed in claim 11 wherein said first softness is within the range of 55-75 D Shore hardness, said second softness is within the range of 30-45 D Shore hardness, and said third softness is less than said first softness and within the range of 55-75 D Shore hardness. 
     
     
       13. A catheter as claimed in claim 12 wherein said endmost section, said other section and said overcoat are color coded, each with a distinct color. 
     
     
       14. A catheter as claimed in claim 13 wherein said blended regions exhibit a color blend generally indicative of said incrementally increasing softness characteristic. 
     
     
       15. A catheter as claimed in claim 14 wherein the blended region between said other section and said overcoat contains incrementally greater amounts of said overcoat dependent upon the distance to said distal end of said catheter. 
     
     
       16. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof;   wherein at least one of said blended regions has an axial length substantially equal to an axial length of one of said endmost section and said other section.   
     
     
       17. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof;   wherein an outer dimension of said endmost and said other tubular section is substantially equivalent to an outer dimension of said overcoat.   
     
     
       18. A catheter as claimed in claim 17 wherein said catheter body is made of a high temperature thermoplastic having a low coefficient of friction and said endmost section protrudes beyond the distal end of said catheter body. 
     
     
       19. A catheter as claimed in claim 17 wherein said first softness is within the range of 55-75 D Shore hardness, said second softness is within the range of 30-45 D Shore hardness, and said third softness is less than said first softness and within the range of 55 - 75 D Shore hardness. 
     
     
       20. A catheter as claimed in claim 17 wherein said endmost section, said other tubular section and said overcoat are color coded, each with a distinct color, and said blended regions exhibit a color blend generally indicative of said incrementally increasing softness characteristic. 
     
     
       21. A catheter as claimed in claim 17 wherein said low temperature thermoplastic overcoat, said low temperature thermoplastic endmost section, and said low temperature thermoplastic other section all melt at temperatures below approximately 300 degrees. 
     
     
       22. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof;   wherein said endmost section, said other tubular section and said overcoat are color coded, each with a distinct color, and said blended regions exhibit a color blend generally indicative of said incrementally increasing softness characteristic.   
     
     
       23. A catheter as claimed in claim 22 wherein said catheter body is made of a high temperature thermoplastic having a low coefficient of friction and said endmost section protrudes beyond the distal end of said catheter body. 
     
     
       24. A catheter as claimed in claim 22 wherein an outer dimension of said endmost and said other tubular section is substantially equivalent to an outer dimension of said overcoat. 
     
     
       25. A catheter as claimed in claim 22 wherein said first softness is within the range of 55-75 D Shore hardness, said second softness is within the range of 30-45 D Shore hardness, and said third softness is less than said first softness and within the range of 55-75 D Shore hardness. 
     
     
       26. A catheter as claimed in claim 22 wherein said low temperature thermoplastic overcoat, said low temperature thermoplastic endmost section, and said low temperature thermoplastic other section all melt at temperatures below approximately 300 degrees Centigrade. 
     
     
       27. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof;   wherein the blended region between said other tubular section and said overcoat contains incrementally greater amounts of said overcoat dependent upon the distance to said distal end of said catheter.   
     
     
       28. A catheter as claimed in claim 27 wherein said catheter body is made of a high temperature thermoplastic having a low coefficient of friction and said endmost section protrudes beyond the distal end of said catheter body. 
     
     
       29. A catheter as claimed in claim 27 wherein an outer dimension of said endmost and said other tubular section is substantially equivalent to an outer dimension of said overcoat. 
     
     
       30. A catheter as claimed in claim 27 wherein said first softness is within the range of 55-75 D Shore hardness, said second softness is within the range of 30-45 D Shore hardness, and said third softness is less than said first softness and within the range of 55-75 D Shore hardness. 
     
     
       31. A catheter as claimed in claim 27 wherein said endmost section, said other tubular section and said overcoat are color coded, each with a distinct color, and said blended regions exhibit a color blend generally indicative of said incrementally increasing softness characteristic. 
     
     
       32. A catheter as claimed in claim 27 wherein said low temperature thermoplastic overcoat, said low temperature thermoplastic endmost section, and said low temperature thermoplastic other section all melt at temperatures below approximately 300 degrees Centigrade. 
     
     
       33. An intravascular catheter having a progressively compliant distal end region comprising: an elongated catheter body having an overcoat of low temperature thermoplastic thereon, said overcoat having a first softness characteristic, said catheter having a distal end region defined by:   an endmost, low temperature, thermoplastic tubular section having a second softness characteristic that is significantly greater than said first softness;   another low temperature, thermoplastic tubular section having a third softness characteristic that is medium with respect to said first and second softness, said other tubular section disposed between said endmost section and said overcoat; and,   blended tubular regions formed by heated diffusion of said endmost section with said other tubular section and said other tubular section with said overcoat, each said blended region having respective incrementally increasing intermediate softness characteristics over predetermined lengths thereof;   wherein said low temperature thermoplastic overcoat, said low temperature thermoplastic endmost section, and said low temperature thermoplastic other tubular section all melt at temperatures below approximately 300 degrees Centigrade.